Art of cracking hydrocarbons



Feb. 23, 1937.

K. A. BEACH 2,071,723

ART OF CRACKING HYDROCARBONS Filed May 4, 1931 2 Sheets-Sheet 1 INVENTOR fife/M2779 4.52406 ATTORNEYS Feb. 23, 1937. K. A. BEACH ART OF CRACKING HYDROCARBONS Filed May 4, 1931 2 Sheets-Sheet 2 INVENTOR- QM @M M MM ATTORNEYS patented Feb. 23,

ART OF CRACKING HYDROCARBONS Kenneth Albert Beach, Chester, Pa., assignor to Sinclair Refining Company, New York, N. Y., a

corporation of Maine Application May i, 1931, Serial No. 534,908

Claims.

This invention relates'to improvements in the combined vapor phase cracking of oils, such as gas oil character or kerosene character stocks, for the production of' lower boiling oils, such as gasoline, and the coking of heavy oils, such as crudes, topped crudes, flux oils, other residual oils and the like.

In certain aspects, the invention relates to modifications of the operations described in applications filed February 18, 1929 and February 19, 1929, Serial Numbers 340,996 and 341,214, respectively, by Harry L. Pelzer.

According to this invention, the hot vapor mixture from a vapor phase cracking operation, while still at high temperature, is passed in intimate contact with a liquid oil mixture to be reduced to coke in a' receptacle adapted to receive an accumulating charge of coke and heating gases escaping from the vapor phase cracking operation, and'heating gases, from which heat absorbed in the vapor phase cracking operation has been abstracted, arepassed over this receptacle, a coke product being periodically discharged from this receptacle. The major part of the heat for coking the liquid oil mixture in the receptacle is supplied internally by the hot vapor mixture from the vapor phase cracking operation. A minor part of the heat for coking the liquid oil mixture in the receptacle is supplied externally by the heating gases escaping from the vapor phase cracking operation. The hot vapor mixture from the vapor phase cracking operation is, with advantage, introduced into the coking receptacle before its temperature falls below 950 F., or better 1050 F., and usually it is, with advantage, introduced into the coking receptacle at the maximum possible temperature. The temperature of the heating gases passing over the coking receptacle is advantageously limited to limit the rate of heat transfer through the walls of the coking receptacle, for example to a temperature higher than but not more than 300 F., or better 200 F., higher than the temperature prevailing within the coking receptacle. The invention includes advantageous means for controlling the temperature of the heating gases passing over the coking receptacle.

The invention may be carried out, for example, with a coking receptacle and a scrubbing receptacle, in which entrained oils or tarry material'is separated from the hot vapor mixture discharged from the coking receptacle, arranged and operated as described in the previously mentioned application Serial Number 340,996. The invenl' tion may also be carried out, for example, in a series of cycles with a seriesof receptacles serving successively as scrubbing receptacles and coking receptacles arranged and operated as de-' scribed in the previously mentioned application Serial Number 341,214. In this instance, the invention includes a special embodiment of particular advantage.

According to the invention, inthis aspect, the

hot vapor mixture from the vapor phase cracking operation, while still at high temperature, is passed successively through a charge of coke, produced as in the next recited step but in a preceding cycle, through a liquid oil mixture to bereduced to coke in a receptacle adapted to receive an accumulating charge of coke, and through a scrubbing operation, and heating gases, from which heat absorbed in the vapor phase cracking operation has been abstracted, are passed successively over the receptacle containing the first mentioned charge of coke and then over the receptacle containing the liquid oil mixture being ccked. In the succeeding cycle, as described in the. previously mentioned application Serial Number 341,214, the receptacle containing the first mentioned charge of coke is cut out of the series and the coke product is discharged, the receptacle in which the liquid oil mixture was coked becomes the receptacle containing the charge of coke throughwhich the hot vapor mixture from the vapor phase cracking operation first passes and over which the heating gases therefrom first, pass, and the receptacle in which the scrubbing operation was carried out becomes the receptacle in which the liquid oil mixture is coked, and so on. Thus, in each cycle, in this embodiment of the invention, the heating gases pass first over a receptacle containing a charge of coke, assisting in drying this coke and then over a receptacle in which a liquid oil mixture is being ccked.

The invention will be further described in connection with the accompanying drawings which illustrate, in Fig. 1, diagrammatically and con ventionally, one form of apparatus, in elevation and partly in section with parts broken away, adapted for carryingout the invention, and in Figs. 2-8, one arrangement of a plurality of coking receptacles. It is to be understood that, in practice, where more than one coking receptacle is used the cokingreceptacles areusually arranged as a compact group rather than as diagrammed in- Fig. 1 in which the necessities of pictorial representation make several of the connections and flues appear much longer in proportion to the apparatus than they need to be. Referring particularly to Figs. 2-8, Fig. 2 is an elevation in section on line 2-2 of Fig. 4, Fig. 3 is-an elevation in section on line 3--3 of Fig.4, Fig.4 isa plan in section on line 44 of Fig. 2, Fig. 5 is'a' plan in section on line 55' ofFig. 2, Fig. 6' is a plan in section on line 6-6 of Fig. 2, Fig-.- 7;

is a plan in section on line 'I--| of Fig. 2 and Fig. 8 isan elevation in section on'line 8-0 in each of Figs.4'7-.' It will be'understood that the" invention can be carried out in other and different forms of apparatus and that this further description is intended as exempliflcation of the invention.

Referring to the drawings, in carrying out the invention in the apparatus illustrated, the hot vapor mixture from the vapor phase cracking operation carried out in the heater 21, without substantial cooling, may be introduced, for example, into the receptacle A in which it is passed through a charge of coke and then into the receptacle B in which it is passed through a charge of oil to be reduced to coke or directly into the receptacle B in which it is passed through a charge of oil to be reduced to coke and heating gases, escaping from the furnace 28 in which the heater 2? is arranged, may be passed, by means of flue 9, for example, over the receptacles A and B in succession or over the receptacle B. The receptacles A, B, C, and D correspond in arrangement and in operation, although the primary function of individual receptacles may change during the operation as will appear.

The vapor phase cracking operation proper may be carried out, for example, as described in an application filed June 13, 1927, Serial Number 198,621, by Harry L. Pelzer, and the hot vapor mixture from the digesting drums discharged directly into the receptacle in which the charge of oil is being reduced to coke, or the digesting drums may be omitted and the hot vapor mixture from the heater discharged directly into the receptacle in which a charge of oil is being reduced to coke.

In the apparatus illustrated, the vapor phase cracking operation proper is carried out in the heater 21 comprising a group of series connected heating tubes arranged in the heating flue of the furnace 28. Hot products of combustion from the fire-box 3|, to which air for combustion is supplied preheated by means of the air heater 32 arranged in the stack 33, pass downwardly through the heating flue in which the heater 2'! is arranged and escape through the flue 9. These escaping heating gases are drawn through one or more of the heating chambers 4|, 42, 43, and 44 in which the receptacles A, B, C, and D are arranged, respectively, by means of a fan or blower 34. Ducts 35 and 36, including dampers 31 and 38 respectively, are provided to afford accurate control of the temperature of the heating gases passing over the receptacles arranged in the heating chambers 4|-44. Opening or increasing the opening of the damper 37 increases the temperature of these heating gas s and opening or increasing the opening of the damper 38 decreases the temperature of these heating gases. Another part of the heating gases discharged by fan 35 may be recirculated through the heating flue in which the heater 2? is arranged by means of ducts 39 provided with dampers as shown. The remaining gases discharged by the fan 34 are discharged through duct 46 to the stack 33.

Oil is supplied to the heater 2'! through connection 45 and the hot oil products of the vapor phase cracking operation carried out therein are discharged through connection 46. The series of receptacles, illustrated as four, may include three, four and more receptacles. The several receptacles are provided with removable heads or the like for the discharge of the coke product formed therein. In the apparatus illustrated, the hot vapor mixture discharged from the vapor phase cracking operation proper through connection 46 may be introduced into the lower end of any of the series of receptacles A, B, C, and D through the connections 41 and 48, 49 and H], 5|] and 5|, or 52 and 53, respectively, or it may be by-passed directly to connection 30 through connection 54. The oil to be reduced to coke may be supplied to the lower end of any of the series of receptacles A, B, C, and D through connection 55, by means of the valved branches illustrated. The hot vapor mixture escaping from the upper end of any of the series of receptacles may be discharged into the lower end of the next receptacle in the series by means of the connections 29, 56 and 16, 51 and 5|, 68, 58 and 53 or 69, 59 and 48. The hot vapor mixture escaping from the upper end of any of the series of receptacles may be discharged through the connection 30 by means of connections 69, 6|, 62 or 63. Connection 64, for supplying steam, and connection 65, communicating with the condenser 66, are provided for steaming out any of the series of receptacles the connections 64 and 65 being connected to each of the receptacles by means of the valved branches illustrated.

The hot vapor mixture discharged through connection 30 is discharged to suitable scrubbing and condensing or scrubbing, fractionating and condensing, or fractionating and condensing or other recovery apparatus, for example, to recovery apparatus such as that described in the previously mentioned application Serial Number 198,621.

In the apparatus illustrated, the upper and lower end of each of the four heating chambers 4|4| is aranged to communicate through a damper, which may be closed completely, with a common transfer flue 61. The lower end of each of the heating chambers 4|44 is arranged to communicate with a damper, which may be completely closed, with the flue 9, and the upper end of each of the heating chambers 4|-44 is arranged to communicate with a damper, which may be completely closed, with the flue ID. This arrangement enables the heating gases supplied through flue 9 to be passed through any one of the heating chambers 4|44 or in succession through any two of them in any order before being discharged through flue l0. Figs. 2-8 illustrate one compact form of this arangement. In Figs 2-8, the dampers are positioned to provide for flow of the heating gases first through the heating chamber in which the receptacle A is arranged and then through the heating chamber in which the receptacle B is arranged, that is the dampers l4, I6, and l! are open and the rest are closed. The course of the heating gases from flue 9 through these two heating chambers in succession to the flue H1 is designated by the series of arrows numbered from to 8 in succession. To provide for flow of the heating gases successively through the heating chambers in which receptacle B and receptacle C are arranged, dampers 5, |8, I9, and 22 are opened and the rest are closed. To provide for flow of the heating gases successively through the heating chambers in which receptacles C and D are arranged, dampers 26, 2|, 23, and 26 are opened and the rest are closed. To provide for flow of the heating gases successively through the heating chambers in which the receptacles D and A are arranged, dampers 24, 25, I2, and I3 are opened and the rest are closed.

Each of the receptacles A, B, C, and D may be operated individually as the coking receptacle in the operation described in the previously mentioned application Serial Number 340,996, heating gases supplied through flue 9 being passed coking receptacle, as in the operationv described in the previously mentioned application Serial Number 341,214.

An, example of such an operation embodying I the invention as carried out in apparatus of the type illustrated will further exemplify the invention:

Fires are started and the heating furnace 28:

heated by circulation through the heater 2'! while the heating furnace 28 is being brought to operating temperatures. When the heating furnace 28 has been brought to operating temperatures, the circulation of gas oil or kerosene or other stock to be subjected to the vapor phase cracking operation is started through the heater 21.

This stock may be a raw stock, for example, or an intermediate condensate separated from the vapors discharged through connection 30, for example, or a mixture of the two, for example. By the time the circulation of the stock to be subjected to the vapor phase cracking operation is started through the heater 21, the receptacle B is filled about one-third full, more or less, with the stock to be reduced to coke, and when the circulation of the stock to be subjected to the vapor phase cracking operation is started through the heater 2! the hot vapor mixture from the vapor phase cracking operation is discharged through the charge of oil to be reduced to coke in the receptacle A and the hot vapor mixture from the receptacle A is subjected to a scrubbing operation by being discharged through the liquid body of oil maintained in receptacle B, the hot vapor mixture from the receptacle B being discharged through connection 3|]. During this step of the operation, the stock to be reduced to coke is supplied to the receptacle B at a rate such that this receptacle is approximately full at the end of this step of the operation. When the charge of oil in the receptacle A has been reduced to coke and when a sufiicient charge of oil has accumulated in receptacle. B, to be subjected to the coking operation, the hot vapor mixture from receptacle B is passed through a liquid body of oil in the receptacle C, to which an initial charge of oil has been supplied as previously described in connection with the operation of receptacle B in the preceding step of the combined operation. The hot vapor mixture from the vapor phase cracking operation is passed through the charge of coke in the receptacle A for some timeafter the coking opera,- tion in receptacle B has been initiated to assist in strip-ping the charge of coke in receptacle A of volatile matter. When the charge of coke in receptacle A is sufficiently free of volatile matter, the hot vapor mixture from the vapor phase cracking operation is discharged directly into the receptacle B, the receptacle A is steamed out through condenser 66 and at the termination of the steaming out operation the charge of coke in receptacle A is removed and this re.-

ceptacle is cleaned to be ready to receive-a charge of oil for carrying out the scrubbing operation during the further step of the combined operation in which a charge of oil is being reduced to coke in the, receptacle D.

The heating gases escaping from the heating furnace 28' through flue 9 are passed through the heating chamber in which the receptacle containing the initial charge of oil to be, reduced to coke.

' is arranged, the heating chamber 4| in which the receptacle A is arranged, for example, while the system is being brought to operating temperatures. While the initial charge of oil is being reduced to coke in the receptacle A, for example, the heating gases are passed from the flue 9 through the heating chamber 4| to the flue Ii). When the coking operation in the receptacle A has been completed and the coking operation in the receptacle B is initiated, the scrubbing operation then being carried out in receptacle C, the heating gases are passed successively through the heating chambers 4| and 42, the several dampers being illustrated, in Fig. 1 as well as in the remaining figures, as positioned to provide for this flow of the heating gases. The heating gases are usually passed through the heating chamber 4|, for example, as long as the hot vapor mixture from the vapor phase cracking operation is beingpassed through the charge'of coke in the receptacle A. The passage of heating gases to the heating chamber 4| may be terminated somewhat before the passage of the hot vapor mixture from the vapor phase cracking operation through the charge, of coke in the receptacle A is terminated, or if may be continued during the period or a portion of the period during which the receptacle A is being steamed out. The heating gases are not normally passed through the heating chamber in,

which the receptacle in which the scrubbing operation is being carried out is arranged, but they may be passed through this heating chamber toward the end of the period during which the receptacle arranged therein is utilized for the scrubbing operation. As the coking operation proper is advanced to successive receptacles in the series, the circulation of the heating gases from the vapor phase cracking operation through the heating chambers in which the successive receptacles are arranged is similarly advanced. When the coking operation proper is being carried out in the receptacle B, for example, the heating gases from the vapor phase crack ng operation are passed through the heating chamber 42, when in the receptacle C through the heating chamber 43 and when in the receptacle D through the heating chamber 44. While the coking operation proper is being carried out in receptacle B anda charge of coke is being stripped of volatile matter in receptacle A, the heating gases from the vapor phase cracking operation may be passed successively through the heating chambers 4| and 42, while the coking operation is being carried out in receptacle C and a charge of coke is being stripped in receptacle B, the heating gases may be passed successively through the heating chambers 42 and 43, etc.

The hot vapor mixture from the vapor phase cracking operation may be discharged through connection 46 at a temperature, for example, in the neighborhood of 110.0-1120 F., and the hot vapor mixture from the combined operation may be discharged through connection 30 at a temperature, for example, in the neighborhood of GEO-800 F. The heating gasesv passing through the fliiei9; may have a. temperature, for: example,

in the neighborhood of 950-1200 F, and the heating gases passing through the flue l0 may have a temperature, for example, in the neighborhood of 850-1100 F.

The invention has a number of advantages, many of which will be apparent from the foregoing description. The invention makes all of the heat supplied in the heating gases from the vapor phase cracking operation, above the temperature at which the coking operation is being carried out, available for the coking operation proper. Losses through radiation of heat so supplied to the coking operation can be completely prevented; some additional heat may also be supplied to the coking operation proper from the heating gases. In these respects the invention provides for an increase in capacity of the combined vapor phase cracking and coking system. The passage of the heating gases from the vapor phase cracking operation over the receptacles in which the coking operation was carried out while at a temperature somewhat above that prevailing in the coking receptacles also assists ready removal of the coke produced from the coking receptacles and promotes easy cleaning of these receptacles. The mild external heating so provided modifies the formation of coke adjacent the walls of the receptacles so that it tends to leave these walls relatively clean. This latter advantage is an advantage of peculiar importance in such combined operations.

I claim:

1. In a combined vapor phase cracking and coking operation, the improvement which comprises supplying a liquid oil mixture to be reduced to coke toa receptacle adapted to receive an accumulating charge of coke, passing the hot vapor mixture from the vapor phase cracking operation before the temperature of the said vapor mixture falls below 959 F. in intimate contact with said liquid oil mixture to be reduced to coke in said receptacle and thereby supplying the major part of the heat for coking the said liquid oil mixture, simultaneously separately passing hot combustion gases escaping from the vapor phase cracking operation at a temperature slightly higher than the temperature prevailing within said receptacle over the said receptacle and thereby supplying a minor part of the heat for coking the said liquid oil mixture, reducing said liquid oil mixture to coke in said receptacle by said heating operations and periodically discharging the coke produced from said receptacle.

2. In a combined vapor phase cracking and coking operation, the improvement which comprises supplying a liquid oil mixture to be reduced to coke to a receptacle adapted to receive an accumulating charge of coke, passing the hot vapor mixture from the vapor phase cracking operation before the temperature of the said vapor mixture falls below 950 F. in intimate contact with said liquid oil mixture to be reduced to coke in said receptacle and thereby supplying the major part of the heatfor coking the said liquid oil mixture, simultaneously separately passing hot-combustion gases escaping from the vapor phase cracking operation at a temperature higher than but not more than 300 F. higher than the temperature prevailing within said receptacle over the said receptacle and thereby supplying a minor part of the heat for coking the said liquid oil mixture, reducing said liquid oil mixture to coke in said receptacle by said heating operations and periodically discharging the coke produced from said receptacle.

3. In a combined vapor phase cracking and coking operation, the improvement which comprises supplying a liquid oil mixture to be reduced to coke to a coking receptacle adapted to receive an accumulating charge of coke, passing the hot vapor mixture from the vapor phase cracking operation before the temperature of the said vapor mixture falls below 950 F. in intimate contact with said liquid oil mixture to be reduced to coke in said receptacle and thereby supplying the major part of the heat for coking the said liquid oil mixture, simultaneously separately passing hot combustion gases escaping from the vapor phase cracking operation at a temperature higher than but not more than 200 F. higher than the temperature prevailing within said receptacle over the said receptacle, reducing said liquid oil mixture to coke in said receptacle by said heating operations, and periodically discharging the coke product from the said receptacle.

4. In a combined vapor phase cracking and coking operation, the improvement which comprises passing the hot vapor mixture from the vapor phase cracking operation through a first receptacle and a second receptacle in succession, said vapor mixture subjecting a charge of coke to a drying operation in the said first receptacle thereby stripping said coke charge of volatile matter contained therein and simultaneously reducing a charge of liquid oil to coke in the said second receptacle, and during said drying and said coking operations, separately passing hot combustion gases escaping from the vapor phase cracking operation first over the said first receptacle and then over the said second receptacle in succession.

5. In a combined vapor phase cracking and coking operation, the improvement which comprises passing the hot vapor mixture from the vapor phase cracking operation through a first and a second receptacle of a series in succession, said vapor mixture subjecting a charge of coke to a drying operation in the said first receptacle thereby stripping said coke charge of volatile matter contained therein and simultaneously reducing a charge of liquid oil to coke in the said second receptacle, and during said drying and said coking operations, separately passing combustion gases escaping from the vapor phase cracking operation first over the said first receptacle and then over the said second receptacle in succession, then passing the hot vapor mixture from the vapor phase cracking operation through the said second and a third receptacle of the series in succession, subjecting a charge of coke to a drying operation in the said second receptacle thereby stripping said coke charges of volatile matter contained therein and simultaneously reducing a charge of liquid oil to coke in the said third receptacle, and during said drying and said coking operations, separately passing combustion gases escaping from the vapor phase cracking operation first over the said second receptacle and then over the said third receptacle in succession, and discharging coke from the said first receptacle, then passing the hot vapor mixture from the vapor phase cracking operation through the said third and a succeeding receptacle of the series, as through the second and third, and separately passing combustion gases escaping from the vapor phase cracking operation over the said third and succeeding receptacles of the series, as over the second and third, and discharging coke from the said second receptacle, and so on.

KENNETH ALBERT BEACH. 

